Cannulae are devices which connect items of hardware or drainage vessels to a patient's body. During heart surgery, for example, a patient's blood is oxygenated and circulated by an artificial heart lung machine. A surgical incision is made into the patient's aorta wherein a cannula is surgically secured such that the outlet end is directed into and along the route of the aorta.
With conventional cannulaes, there have been flow problems associated with the relatively high velocity of blood into the aorta. There are also concerns over the possible dislodgement of fatty tissue from the vicinity of the aorta and its potentially serious implications. Specifically, there is concern that blood emerging at high velocity from cannulae could damage the aortic wall and/or dislodge atheromatous plaque and hence cause embolic phenomena. Additionally, another concern is that high velocities (and related high impact pressures) might disturb the distribution of flow to the blood vessels.
Atheromatous plaque can be released into the general blood circulation when there is cannulation of the aorta, manipulation of the heart and ascending aorta, and application or release of the cross-clamp or side biting clamp to the aorta. Furthermore, boluses of air or “surgical air” can enter the general blood circulation when there is cannulation of the heart or aorta and removal of the cross clamp, at the site of venous cannulation and when a surgical intervention requires the opening of the cardiac chambers. As such, the use of alternative cannulas such as the “soft flow” cannula or “dispersion” cannula have been popular. These cannulas are designed to not have a central flow through a central orifice to avoid having a high velocity jet of blood hitting the back side of the blood vessel wall. However, the velocity of the blood flow from current “soft flow” cannulas are still high, at about 4-6 liters per minute. The gentle flow cannula of the present invention is able to descrease the blood flow even further.
In any type of surgery, especially cardiac surgery, time is of the essence. The less time it takes a surgeon to perform the surgery the better. Currently, incisions are first made into a blood vessel with a surgical knife. The surgical knife is then removed and the cannula is inserted into the incision. The time to perform these two procedures may be drastically reduced by the present invention.